Book contents
- Frontmatter
- Dedication
- Contents
- Foreword
- Preface
- User Guide
- Charles Messier
- The Observations
- The Catalog
- Statistics of the Messier objects
- Visual observation of the Messier objects
- Photography of the Messier objects
- The 110 Messier objects
- M 1
- M 2
- M 3
- M 4
- M 5
- M 6
- M 7
- M 8
- M 9
- M 10
- M 11
- M 12
- M 13
- M 14
- M 15
- M 16
- M 17
- M 18
- M 19
- M 20
- M 21
- M 22
- M 23
- M 24
- M 25
- M 26
- M 27
- M 28
- M 29
- M 30
- M 31
- M 32
- M 33
- M 34
- M 35
- M 36
- M 37
- M 38
- 39
- M 40
- M 41
- M 42
- M 43
- M 44
- M 45
- M 46
- M 47
- M 48
- M 49
- M 50
- M 51
- M 52
- M 53
- M 54
- M 55
- M 56
- M 57
- M 58
- M 59
- M 60
- M 61
- M 62
- M 63
- M 64
- M 65
- M 66
- M 67
- M 68
- M 69
- M 70
- M 71
- M 72
- M 73
- M 74
- M 75
- M 76
- M 77
- M 78
- M 79
- M 80
- M 81
- M 82
- M 83
- M 84
- M 85
- M 86
- M 87
- M 88
- M 89
- M 90
- M 91
- M 92
- M 93
- M 94
- M 95
- M 96
- M 97
- M 98
- M 99
- M 100
- M 101
- M 102
- M 103
- M 104
- M 105
- M 106
- M 107
- M 108
- M 109
- M 110
- Glossary of technical terms
- Index of figures
- Index of sources
M 30
from The 110 Messier objects
Published online by Cambridge University Press: 05 August 2015
- Frontmatter
- Dedication
- Contents
- Foreword
- Preface
- User Guide
- Charles Messier
- The Observations
- The Catalog
- Statistics of the Messier objects
- Visual observation of the Messier objects
- Photography of the Messier objects
- The 110 Messier objects
- M 1
- M 2
- M 3
- M 4
- M 5
- M 6
- M 7
- M 8
- M 9
- M 10
- M 11
- M 12
- M 13
- M 14
- M 15
- M 16
- M 17
- M 18
- M 19
- M 20
- M 21
- M 22
- M 23
- M 24
- M 25
- M 26
- M 27
- M 28
- M 29
- M 30
- M 31
- M 32
- M 33
- M 34
- M 35
- M 36
- M 37
- M 38
- 39
- M 40
- M 41
- M 42
- M 43
- M 44
- M 45
- M 46
- M 47
- M 48
- M 49
- M 50
- M 51
- M 52
- M 53
- M 54
- M 55
- M 56
- M 57
- M 58
- M 59
- M 60
- M 61
- M 62
- M 63
- M 64
- M 65
- M 66
- M 67
- M 68
- M 69
- M 70
- M 71
- M 72
- M 73
- M 74
- M 75
- M 76
- M 77
- M 78
- M 79
- M 80
- M 81
- M 82
- M 83
- M 84
- M 85
- M 86
- M 87
- M 88
- M 89
- M 90
- M 91
- M 92
- M 93
- M 94
- M 95
- M 96
- M 97
- M 98
- M 99
- M 100
- M 101
- M 102
- M 103
- M 104
- M 105
- M 106
- M 107
- M 108
- M 109
- M 110
- Glossary of technical terms
- Index of figures
- Index of sources
Summary
Degree of difficulty 3 (of 5)
Minimum aperture 30mm
Designation NGC 7099
Type Open cluster
Class V
Distance 29,460 ly (R2005) 30,730 ly (CMD, 1999)
Size 100 ly
Constellation Capricornus
R.A. 21h 40.4min
Decl. –23° 11′
Magnitude 7.3
Surface brightness –
Apparent diameter 12′
Discoverer Messier, 1764
History On the 8th of August 1764, Charles Messier found a “nebula” in Capricorn and noted: “It can be seen with difficulty in a simple refractor of 3½ ft; it is round & does not contain any star, 2′ diameter.”
In 1783, with his superior home-made reflectors, William Herschel was able to resolve M 30 into individual stars. He noted: “Towards the north are two rows of bright stars, four or five in a line.” Almost 50 years later, his son John commented in more detail: “Fine cluster; irregularly round, with two projections at its northern side. One is directed from the central brightness and consists of three or four bright stars of 12th magnitude; its position taken with micrometer is 350.4°; the other originates in the preceding side of the center, and is directed in a position 331.7° in a line not passing the center; diameter 6′, stars of 12th magnitude; has a star of 9th magnitude preceding it.” Smyth, observing with a significantly smaller aperture (5.9 inches) than John Herschel, described: “A fine pale white cluster. This object is bright, and from the straggling streams of stars on its northern verge, has an elliptical aspect, with a central blaze; and there are but few other stars, or outliers, in the field.”
Astrophysics The globular cluster M 30 lies at a distance of 30,000 light-years from us, below the galactic plane. Its orbit around the galactic center is inclined at 50° to the galactic disk and it takes 160 million years to complete.
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- Information
- Atlas of the Messier ObjectsHighlights of the Deep Sky, pp. 142 - 143Publisher: Cambridge University PressPrint publication year: 2008